A biological spill procedure has five core steps: alert people nearby, contain the spill and protect yourself, cover it with absorbent material and an effective disinfectant, wait for the full contact time, then clean up, dispose of waste safely and report. The detail changes with the agent, the volume, the location and whether aerosols or sharps are involved.
Spills are among the most common microbiology lab incidents, and the first few minutes decide whether a dropped tube becomes a non-event or an exposure. Auditors look for a written procedure, a stocked kit and staff who know what to do without reaching for the SOP.
A risk-based approach to spills
The WHO Laboratory Biosafety Manual 4th edition (2020) asks labs to base controls on a risk assessment of their actual work. For spills, ask in advance which agents, volumes and concentrations you handle, which procedures produce aerosols and where spills are likely.
The answers set your disinfectant, contact time, PPE, evacuation rules and reporting. A bench spill of a low-risk culture and a broken flask of a high-titre pathogen do not need the same response.
What goes in a microbiology spill kit
Keep a labelled kit near the work area and restock it after every use. A typical kit includes:
- Disinfectant suitable for your agents, as ready-to-use solution, concentrate or tablets, with instructions for making it up
- Absorbent material: paper towels, absorbent pads or granules
- Forceps or tongs, a scoop and scraper or dustpan for broken glass
- Puncture-resistant sharps container and autoclavable biohazard bags
- PPE: disposable gloves (plus heavy-duty gloves for glass), gown or apron, eye protection or face shield, and respiratory protection if your risk assessment requires it
- Warning signs to keep people out of the area
- A copy of the spill SOP and an incident report form
Choosing a disinfectant and contact time
Sodium hypochlorite is widely used because it is broad-spectrum and inexpensive. It loses strength over time and in organic matter, so prepare it fresh at the available chlorine concentration in your SOP, usually stronger for heavy organic loads. It corrodes stainless steel, so rinse metal afterwards.
Commercial disinfectants work if their claims cover your organisms. Whatever you use, respect the manufacturer's or SOP's contact time. Alcohol is a poor spill disinfectant because it evaporates quickly and penetrates organic material poorly.
Step by step: spill scenarios
Small spill on the bench
- Alert people nearby and put on gloves, a lab coat and eye protection.
- Cover the spill gently with paper towels or absorbent pads.
- Pour disinfectant around the edges first, then over the centre, so the spill is not spread outwards.
- Leave for the full contact time.
- Pick up the material with forceps, place it in a biohazard bag, and wipe the area again with disinfectant.
- Remove PPE, wash your hands and record the spill.
Larger spill on the floor
Clear the room, close the door and display a warning sign. Remove contaminated clothing and wash exposed skin. Wait for the time set by your SOP so aerosols can settle or be cleared, then re-enter with the PPE your risk assessment specifies and follow the bench procedure.
Spill inside a biosafety cabinet
Keep the cabinet running and do not pull your hands out quickly. Cover the spill with absorbent material and disinfectant, then after the contact time wipe the work surface, walls and items inside. If liquid has run through the grilles, follow the manufacturer's instructions for the catch area beneath the work surface.
Spill or breakage in a centrifuge
If you suspect a breakage, switch off the motor and keep the lid closed for the time your SOP sets, so aerosols can settle. Move sealed buckets or safety cups unopened to a biosafety cabinet and open them there. If they were not sealed, treat the centrifuge as contaminated: remove glass with forceps and disinfect buckets, rotor and bowl with a product the manufacturer approves.
Spills involving broken glass
Never pick up broken glass with your hands, even when gloved. Use forceps, tongs or a scoop and scraper, place fragments straight into a sharps container, and wear heavy-duty gloves over disposable ones.
Spill response at a glance
| Scenario | Immediate action | Disinfection | Reporting |
|---|---|---|---|
| Small bench spill | Alert others, PPE, cover with absorbent | Edges inwards, full contact time | Spill log; inform supervisor |
| Large floor spill | Evacuate, close door, sign, wait before re-entry | As bench spill, with PPE from risk assessment | Incident report; biosafety officer informed |
| Inside a BSC | Keep cabinet running, cover spill | Surface, walls, items, catch area | Spill log; assess need for cabinet decontamination |
| Centrifuge breakage | Motor off, lid closed, wait | Open sealed buckets in a BSC; disinfect rotor and bowl with approved product | Incident report; review tube and bucket use |
| Broken glass | Do not use hands; use forceps or scoop | Disinfect before and after glass removal | Incident report; note any cuts as exposure |
Exposure first aid and reporting
If material contacts skin, wash with soap and running water. For eye splashes, flush at an eyewash station for the time stated in your first aid procedure. For a cut or needlestick, wash the wound with soap and water without scrubbing. In every case, report to your supervisor and occupational health straight away, because some exposures need prompt medical assessment.
Log every spill, even without exposure. Minor spills reviewed together reveal patterns, such as a container type that keeps failing.
Worked example: a Salmonella culture spill in Kochi
In a food microbiology lab in Kochi, an analyst carries a glass flask of Salmonella enrichment culture by hand from the incubator to the BSC. The flask slips and breaks on the floor, splashing her shoe covers and lower trousers.
She calls out and the room is cleared, the door closed and the spill sign displayed. She bags her shoe covers and lab coat, washes her hands, confirms there was no skin contact and informs her supervisor.
After the SOP waiting period, a trained analyst re-enters with double gloves, a gown and eye protection. He covers the spill with absorbent pads, applies freshly prepared hypochlorite at the SOP strength from the edges inwards and waits the full contact time. Glass goes into a sharps container with a scoop and forceps, and waste is bagged for autoclaving.
The review finds the root cause in the process, not the person: cultures were routinely carried in glass flasks without secondary containment. Actions include closed carriers for all culture movement, unbreakable flasks where suitable and refresher training, tracked as described in our guide to CAPA in laboratories.
Common mistakes
- Spraying disinfectant directly onto a spill, which creates aerosols.
- Wiping up before the contact time is complete.
- Using hypochlorite made up weeks ago.
- Picking up glass with gloved hands.
- Opening a centrifuge immediately after a suspected breakage.
- Not reporting a small spill because nobody was hurt.
- Not restocking the kit.
Key takeaway: Plan spill response before it happens. Base it on a risk assessment, keep a stocked kit nearby, cover gently, respect contact time, never touch broken glass with hands, and report every spill so the lab can fix the cause.
Frequently Asked Questions
What is the first thing to do after a biological spill?
Alert people nearby so nobody walks into the spill, then protect yourself. For a small spill, put on PPE and cover it with absorbent material. For a large spill or one likely to produce aerosols, leave the room, close the door, display a warning sign and inform your supervisor before anyone re-enters.
What should be in a biological spill kit?
A biological spill kit should contain a suitable disinfectant, absorbent material, forceps or tongs, a scoop and scraper for glass, a sharps container, biohazard bags, PPE such as gloves, gown and eye protection, warning signs, the spill SOP and an incident report form. Check and restock it on a schedule.
How long should disinfectant stay on a spill?
Leave the disinfectant for the full contact time stated by the manufacturer or your lab's validated SOP. Contact time depends on the product, its concentration, the organisms involved and the amount of organic material. Wiping it away early is a common reason why spill clean-up fails to inactivate the agent.
Should you wait after a centrifuge tube breaks?
Yes. Switch off the centrifuge and keep the lid closed for the time set in your SOP so aerosols can settle. If sealed buckets were used, open them only inside a biosafety cabinet. If buckets were not sealed, treat the whole centrifuge as contaminated and follow the full spill procedure.
Next steps
Our Laboratory Biosafety and Biosecurity Essentials course covers risk assessment, spill response, PPE and incident management for working labs.
For related reading, see biosafety cabinet classes explained and CAPA in laboratories: root cause to closure. If you would like advice on a course, speak to a counsellor.
Looking for structured certification?
Explore Innoryx courses or speak to a counsellor about the right program for you.